1. Field of the Invention
The invention relates to a vacuum insulation panel (VIP).
2. The Prior Art
The thermal conductivity of insulating plates can be drastically reduced if there is a vacuum in the system. This is known, for example, from U.S. Pat. No. 5,950,450 or German Patent No. DE 4339435. An inexpensive solution for producing a VIP of this type includes a microporous thermally insulating plate which is welded in a vacuum-tight manner into a composite foil. The composite foil used is either a prefabricated foil pouch, generally a sealed-edge pouch, or two foil blanks which are fed to the process. In both production variants, a central projecting section of foil remains on the VIP after evacuation as a result of the weld seams and/or plate shrinkage. This projecting section of foil causes problems when the VIPs are combined to form insulating enclosures such as transport boxes, since the thermally insulating plates cannot be fitted together without gaps and therefore heat bridges are formed, reducing the otherwise excellent insulating action.
To solve this problem, German Patent No. DE 10058566 to va-Q-tec proposes folding away the projecting section of foil using a folding technique. On a large industrial scale, this represents a complex and therefore expensive solution.
Another possible way of eliminating the disruptive influence of the projecting sections of foil consists in joining together the individual plates via plug-fit connections made from unevacuated insulating materials when an insulating enclosure is assembled. This is proposed in German Patent No. DE 100 58 565 to va-Q-tec.
Furthermore, there is a known cost-intensive process in which a vacuum-insulated plate is inserted into a thermoformed multilayer film and is closed off in a gastight manner with a planar film. As a result, the projecting section of film is always at the outer edge of the panel. Due to the use of the thermoformed films, this process is very cost-intensive and is also very inflexible with regard to the use of different geometries. Since films which contain metal layers (i.e. foils) cannot be thermoformed, thermoformed multilayer films do not include any metal layers.